Method of forging a headed element



Oct. 27, 1953 J, H. MANSFIELD 2,656,739

METHOD OF FORGING A HEADED ELEMENT Filed on. a, 1950 s Sheets-Sheet 1 mom, c' uelu' n +mlqm ieiol mzkmfl Oct.'27, 1953 J. H. MANSFIELD 2,656,739

METHOD OF FORGING A HEADED ELEMENT Filed Oct. 6, 1950 asheets-sneet 3 Patented Oct. 27, 1953 UNITED STATES PATENT OFFICE Judson H. Mansfield, Rockford, Ill., assignor to Greenlee Bros. & 00., Rockford, 111., a corporation of Illinois Application October 6, 1950, Serial No. 188,822

2 Claims.

This invention relates to headed elements of the type from which tools such as wood bits are made having a pyramidal shape to interfit with the jaws of a drill chuck or the like. Such tool heads or so-called bit squares have heretofore been formed by hot forging which requires extreme skill on the part of the operator in order to form the sides of the pyramid with square corners and necessitates subsequent machining of the surfaces.

The primary object of the present invention is to provide a novel head construction of the above character which permits the latter to be formed by cold forging without any subsequent machining.

Another object is to shape the flat sides and the base of the pyramid in a novel manner such that the sides may be formed by lateral compression of a conical frustum.

The invention also resides in the novel method of and the die for shaping the pyramidal heads.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Figures 1 to 3 are elevational views illustrating the successive steps in the formation of the improved tool head.

Figs. 4 and 5 are cross sections taken respectively along the lines 44 and 5-5 of Figs. 2 and 3.

Fig. 6 is an enlarged elevational view of the finished tool head.

Fig. 7 is an end view.

Fig. 8 is a fragmentary elevational view of the die arrangement used in the final shaping of the tool head.

Figs. 9 and 10 are fragmentary sectional views taken along the line l0--I0 of Fig. 8 and showing the die elements in open and closed positions respectively.

Fig. 11 is a fragmentary section taken along the line I ll I of Fig. 10.

Fig. 12 is an enlarged view of a part of Fig. 11.

While the invention is susceptible of various modifications and alternative constructions and may be practiced in various ways, I have illustrated in the drawings and will herein describe the preferred embodiment and manner of carrying out the invention. It is to be understood that I do not thereby intend to limit the invention by such disclosure but aim to cover all modifications, alternative constructions, and methods, falling within the spirit and scope of the invention as expressed in the appended claims.

The improved tool head indicated generally at It! is upset on one end of a cylindrical blank ll (Fig. 1) one portion l2 of which constitutes the shank of the tool. The head In is of generally pyramidal shape dimensioned to correspond to the hot forged bit squares of standard construction and having four flat side faces I3 which converge axially and intersect a convexly rounded end surface l4 along arcs l8. At the base of the pyramid, the wider ends of the side faces l3 intersect and interrupt a frusto-conica'l surface l5 along an arcuate line I6 whose center terminates near the apex end or the conical surface which intersects the shank l2 around a circular line H.

To facilitate final shaping of the head by cold forging, the adjacent edges 20 of the flat faces I3 are separated from each along the full length of the faces between the arcs l6 and iii of intersection with the end surfaces M and I5 and are connected by narrow facets 2| which form the corners of the pyramid. These facets are of substantially uniform and equal widths throughout their lengths and are slightly rounded in cross section so as to impart a slightly beveled appearance to the corners of the head. At their opposite ends, the edges of the facets merge with the ends of the intersection arcs I6 and I8.

The head H] of the contour described above is formed in one or more heading operations followed by a final cold forging in a separate special die assembly. Preferably, the preliminary heading is accomplished in one step and entirely automatically in a heading machine of well known construction such as' are used in forming the heads of screws and bolts. In the die of the heading machine, the metal at the exposed end of the blank H is upset and simultaneously shaped to form a head 23 of the contour and the dimensions shown in Fig. 2. The head comprises an elongated code 28 merging at its smaller end with a rounded end surface 22 and at the other end intersecting a shorter and inverted conical frustum 25 of a height equal to that of the surface l5 in the final head. The cone 2B is shaped with a non-uniform taper the angle of which decreases progressively from a common line 26 substantially to zero at 21 where the surface merges with the rounded end 22 of the blank. The contour of the surface 28 is important in controlling the proper flow of metal in the final forging step and is determined by a cut and try process for different sizes and shapes of the head [0. i

The shaping of the head to the desired pyramidal shape is effected by compressing the entire length of the conical part 28 and the major base portion of the head 23 radially between four rigid fiat die surfaces 29 preferably having side edges 30 converging upwardly toward each other in the direction of the taper 28 with the edges of the adjacent. surfacesdisposed parallel to each other andlaterally spaced apart short distances in the final'collapsed position of the die as shown in Fig. 12. These surfaces are on the inner sidesof heavy metal blocks 3| which are mounted in a hollow die frame 32 to swingzinxradialrpianesf 33 and 34 (Fig. 11) disposed perpendicular to each other. The blocks areof triangular-horizontal cross section as shown in-Fig." 11 and'at' their upper ends bear against the exterior of a ball 53 which is seated in a., cupeshapedzheadz 49 and defines at its center the fulcrum about which the four die blocks ,3l swing. Theupper block ends are exteriorly confined at 35 by verticalsurfa ces 35= on tlie head 4'9 wl'iiohi's.=slida ble ina ver-ticaYg-uid'eway 5d witliiirthe diefraane 32 and is urged downwardly relative to the'latter by compression springs fi Lugs 31: on the upper ends: of the blocks 33 bear against a= downwardly facing-"surface on: the" slidable head 49; the

faces: of the lugs coming into full? contact with this surface when the blocks are swung together as shown in Figs. l and- 11; A pl-ungerurged downwardly by: a: spring 39' acts on camsurfaces 40"tourge theblbeks '3 apart:

In the present: instance; thepressure for swing ingthe -lower'ends of the blockstogethe-r with sufficient force to forgetlie upset headint'o' the. desired shape is derived by the action oft ogglea l links 4t fulcrumed' at' their: outer. ends ona pins 42 rigidly supported? in the die: frame:-v At' their inner: ends, each linl 1 is. curved: to fit? around. an arcuate surface43 on the lower-end portion of;

the associatedl block; Thus; when the. die frame- 32 is forced: downwardly: from. the: open: position;

show-n'linzfligfi; thetwo pairs of toggle links are straightened forcing the blocks 3.] inwardly about thecenterrofzthesball'3sas afulcrumatoithelimit positionlshown' in: Figs. .1 OI and. 11, these positions r being; determined: accurately: by engagement. of:

aibottom' plate;- 44oni the die frame with the' top". of the; fixture base 45; from: the: latter: is; adaptedx, to pass: through; an

aperturerinrthe bottomiplate 4'4: and ,is recessed;

torreceivethershank: !2:: of' the. upset-"blank... At itSJLIDDGIYBIId}. the: boss 46: is formed. withza'; flat? surface? 417: 011* which" the: lower arcuate: ends 48: of; the? blocks: 3 I: slide: as the. blocks are: swung: inwardlyrby the 2 action of 1; the toggles"; 4 Ii In operation; the shankofthe-work blankzis: insert'edrin: a hole-in'theboss 4&while: the-:die.

frame'32is::raised.as shown in Fig. 8;.the upset:

head onithewblankthus beingralined withithe downwardly flaring opening: defined; by: the surfaces 29; of the: die. blocks: 3 I. latter-arespread:apartzas. show-min Fig. Sk-by the.-

action of; the springs 5 l whichiforce; the .slidable. head; 49- dow'nwardlyy and. fiex: the. toggle links: 41;. this-movement being limited by engagement; of. the lowerwendsAa-of the. diezblocks with1the= The? forging operation; is effected by" moving: the; die supporting frame 32 downwardlvtoi the? limitwdetermined by engagement of the bottom plate; 44:1with; the;top: of'the fixturebase 45; As".

the die: framez approaches: this 1 position-,- the; boss 46:: enters; the hole. in the: bottom: plate and: the: arcuate surfaces 48 thereon engage the dieblocle:

surfaces 411: thus: interrupting the: downward A. boss; 45;- upstanding:

At this time; .the:

movement of the die blocks. At this time, the parts will be positioned as shown in Fig. 9, the upset head of the work blank being disposed within the die surfaces 29 substantially at the level of the inner toggle pivots 43.

Now, as the die frame continues its downward movement, the outer pivots 42 of the toggles move downwardly whilethe inner pivots and the die blocks remain fixed vertically. This results in straightening the toggles and as a consequence forcing the die blocks 3! inwardly, the lower ends 48ridingalong;the. surface 41 of the fixture. The four die faces 29 first engage the blank head at oppositeends of the elongated conical surface 28" andat points'angularly spaced around the latter. As the compression of the head continues, thevdisplacediametal.fiows upwardly only by virtue of the particular contour of the surface 28 andthehead of the blank is elongated upwardly but only above the junction line 26.

By: the time that? the die: frame reaches. its limit downward: position. against the" top of." the. fixture base 45iasshowninFig; 11; the sides of theidie blocks: 3 i. will have; come. into: close proxclose=together, about .010: ofaninch; but'nevere thelessspaced apart:

above, takesplace-uniformly along. the? openings between the blocks-imspite: of: the upward dis-- placement of the metal and. elongation: of." the:

head. As .a. result1of: this natural metalflow; the.

facets 2| between the flat sides E3 of the-pyramid are formed. to; a. slightlyrounded: contour-and curve: gradually along. their: edges into coincie dencerwith'.theiplane"ofx'the surfaces l3. Thus,. the facets are of substantially uniform: width;

throughoutitheirrlength even though theyareulot actually shapedby adie; surface.

When the die headiiszagain raised,,the springs 5| willhold the dieblocks 3| downwardly against. the. fixtures boss" 46.- until, the' bottom plate 44' engages the blockends. 48. movement betweenithesdie'frame and theblocks, thee. toggles: are: flexed permitting the blocktobe spread apart by the action;.of; the:springi39'; The head lllthusfinishediton the work blank is released from the die and" the blank may be withdrawn from the fixture after further upward retraction of" thedie frame.

I claim as my invention:

1. The method of cold forging a head ofpyramidal shape onone-end of a cylindricar bar which comprises rounding the bar end and-up setting the adjacent portion of the ear-to form" an outwardlygfiaring frusto-conical surface and a longer conical surface of decreasing taper and ing said die surfaces radially toward" each otherto compress the entire length of said' second conical'surface and the adjacent base portion" ofsaid firstconical surface inwardly until the side'edges ofsaid die surfaces are-disposed ad jacent= but" laterally spaced from each" other wherebythe natural fiow of 'metal' forms a. nar- I row facetx atzeachxcornerof "the resultingpyramidi.

This allows .the. displaced. metal to. flow outwardly but. SllChl flow is small.- and, with the blank head contouredras'described In this relative 2. The method of cold forging a head of pyramidal shape on a cylindrical metal bar which comprise upsetting one end portion of the bar to form a rounded end, a frusto-conical surface spaced from and flaring outwardly toward such end, and a longer conical intermediate surface of shorter axial length than said pyramidal head converging gradually from intersection with the base of said first surface into mergence with the surface of said rounded end, positioning the partially formed head between four rigid flat die surfaces converging along said intermediate surface substantially equidistantly therefrom and each having straight side edges converging in the direction of the taper of said intermediate surface, and forcing said die surfaces radially toward each other to compress the entire length of the intermediate conical portion and the adjacent base portion of the first conical portion inwardly until said side edges of the die surfaces are disposed adjacent but laterally spaced from each other whereby to elongate said intermediate portion into said pyramidal head and, by the natural flow of metal, form a narrow unforged facet of substantially uniform width at each corner of the pyramid.

JUDSON H. MANSFIELD.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 75,454 Paynew Mar. 10, 1868 88,760 Whitehouse Apr. 6, 1869 128,083 Wiley et a1. June 18 1872 626,234 Hubbard, Jr. June 6, 1899 943,335 Blalreslee Dec. 14, 1909 1,184,111 McPherson May 23, 1916 1,934,752 Wilcox Nov. 14, 1933 1,957,924 Wilcox May 8, 1934 2,024,593 Moore Dec. 17, 1935 

